They assume you have plenty of knowledge so you end up asking loads of questions. Best to do the OFTEC 50 to start with (which doesn't qualify you to do much!) otherwise you'll be likely to fail the main exams (which are not easy!)
It is hands on learning but limited. I trained at AGA, who I'd recommend, and we serviced a pressure jet and a gravity fed cooker. Five day course and these were two of the afternoons. The rest of the time is spent learning the rules and how to qualifiy as a technician.
And when you finish you feel very confused and learn that you have to spend another £1,000 or so on equipment. And they don't teach you how to do water repairs and there is next to nothing on motor valves, programmers or stuff like that.
I don't do gas (yet?) but the reason I did OFTEC was I live in the sticks and didn't want people phoning me up saying that "My heating won't work", then finding it was a boiler problem and then having to give the customer to a competitor.
Hope this helps and this is from my perspective only. Others may think quite differently to me.
